1. Field of the Invention
The present invention relates to a coil-type electronic component and its manufacturing method. In particular, the present invention relates to a coil-type electronic component using a soft magnetic alloy suitable for coil-type electronic components that are made small enough to be mounted on the surfaces of circuit boards, as well as a manufacturing method for said coil-type electronic component.
2. Description of the Related Art
Traditionally ferrite cores, cores cut out from thin metal sheets, and compacted powder magnetic cores, are used as magnetic cores for choke coils subject to high frequencies.
Metal magnetic materials provide an advantage over ferrite in that they can achieve higher saturation magnetic flux densities. On the other hand, metal magnetic materials themselves have low insulation property and must be given insulation treatment.
Patent Literature 1 (Japanese Patent Laid-open No. 2001-11563) proposes compression-molding a mixture of Fe—Al—Si powder having surface oxide film with a binder, and then heat-treating the molded product in an oxidizing atmosphere. According to this patent literature, applying heat treatment in an oxidizing atmosphere allows for formation of an oxide layer (alumina) in areas where the insulation layer on the surface of alloy powder has broken during compression molding, thereby achieving a complex magnetic material offering good DC superimposition characteristics with small core loss.
Patent Literature 2 (Japanese Patent Laid-open No. 2007-27354) describes a laminated electronic component whose main ingredient is metal magnetic powder, wherein said laminated electronic component is produced by stacking a metal magnetic layer formed by metal magnetic paste containing glass, with conductive patterns formed by conductive paste containing silver or other metal, thereby forming coil patterns inside the laminate, and wherein this laminated electronic component had been sintered in a nitrogen atmosphere at a temperature of 400° C. or above.
The complex magnetic material described in Patent Literature 1 requires a large force at the time of compression molding because molding uses Fe—Al—Si powder having oxide film already formed on its surface.
This material also presents a problem in that it does not support further size reduction if applied to power inductors or other electronic components through which greater current must flow.
The laminated electronic component described in Patent Literature 2 presents a problem in that the production cost may increase because the metal magnetic grains must be coated uniformly with glass and a nitrogen atmosphere is required to control this coating process.
Any discussion of problems and solutions involved in the related art has been included in this disclosure solely for the purposes of providing a context for the present invention, and it should not be taken as an admission that any or all of the discussion were known at the time the invention was made.